El Nio climate pattern has returned

The El Niño climate pattern has returned for the first time since 2003 and will affect the climate in the Southeast for the next three to six months, according to the latest outlook from the Southeast Climate Consortium (SECC).

The SECC is a coalition of six universities, including Florida State University, University of Florida, University of Miami, University of Georgia, Auburn University and the University of Alabama-Huntsville.

While this El Niño event began a little later in the year than most warm events, summer/fall is the usual time when sea surface temperatures may rise and spread across the Pacific, according to the forecast. El Niño normally reaches peak intensity and coverage in the winter months.

Because of this seasonality of El Niño, the first impact felt in the Southeast U.S. is the relative inactivity of the hurricane season. “In spite of predictions to the contrary, 2006 has so far been a quiet tropical season and many are blaming the developing El Niño. El Niño is known to create an environment of high shear (winds changing with height) over hurricane formation regions in the Atlantic, Caribbean, and Gulf of Mexico that hinders hurricane development.

With El Niño continuing to grow and with the hurricane season over half over, we expect the remainder of the hurricane season to continue below average activity,” according to the SECC report.

Partially due to the expected decrease in tropical activity, El Niño actually brings drier than normal conditions (20 percent to 30 percent less rain than normal) to Florida, southern Alabama, and southern Georgia in the months of September and October. “Rainfall from tropical systems is an integral component of the climate of the Southeast in the fall, which is otherwise fairly dry without the impact of a tropical system. El Niño does not have much influence on temperatures during these months September and October,” states the SECC outlook.

Once the colder months arrive (November through March), the classic El Niño climate patterns should establish themselves and control weather during that time. The El Niño is known to bring more frequent storms, excessive rainfall, and cooler temperatures to Florida and coastal Alabama and Georgia.

“Florida can expect 40 to 60 percent more rainfall than normal in the winter months. It is believed that the increase in rain and cloudiness associated with El Niño causes average temperatures to be cooler than normal during the winter months. These cooler temperatures result in greater chill accumulations over the course of the season. While average temperatures are often cooler, El Niño actually reduces the risk of severe cold outbreaks in Florida and the Southeast. The strong subtropical jet stream that is typical of El Niño acts to ‘block’ the intrusions of cold arctic air masses,” according to the forecast.

Turning to more current conditions, the SECC says that after a very dry spring and early summer for most of the area, more plentiful rainfall returned to the Southeast in August and September. As is the usual case for summer precipitation, coverage and accumulations have been highly variable throughout the region.

“Southwest Florida has received soaking rains from tropical storms Alberto and Ernesto along with frequent thundershowers, resulting in a surplus of summer rain. Other areas, the western Panhandle of Florida and southeast Alabama in particular, have remained rather dry. While not offering immediate relief, El Niño should help these areas catch up in the coming winter.”

The SECC predicts the following impacts on Southeastern crops from the latest El Niño:

Winter vegetables (tomato, green peppers): Tomato and green peppers generally yield less during El Niño years than during Neutral or La Niña years. Most soil-borne pathogens and fruit quality problems increase in El Niño years. Fruit quality problems like gray wall are also more prevalent in El Niño years,

Pasture: In general, El Niño years are good for winter pasture due to wetter conditions. However, growth may be slower due to increased cloudiness and consequent decrease in solar radiation.

Row Crops: El Niño impacts are less evident on annual summer crops since its strongest signal occurs during fall, winter and spring. Analysis of historical yield data is a good way to evaluate potential impacts of various row crops. Increased disease pressure and slower development may affect spring sown horticultural crops.